The present invention relates to rolling mills and in particular relates to a method for cooling the mill rolls and apparatus for performing such method.
As is well known, much heat is transferred to the work rolls of a rolling mill at the points of contact between the work rolls and the strip or ingot. In addition to the heat energy generated in reducing metal thickness, in hot-rolling mills heat is transferred to the rolls from the preheated ingot. It is well known that the heat introduced into the work rolls must be dissipated in order to prevent excessive temperature rise, which can destroy the surface finish of the rolls. It is also necessary to control the temperature of the work rolls to ensure that they do not deviate excessively from the predetermined camber.
It has been the common practice heretofore to lubricate and cool the rolls of a rolling mill by flooding the work rolls and strip at the entry side of the mill with a coolant/lubricant liquid consisting of a cooling medium in which one or more lubricants are present. Because of their much higher cooling capacity, it is the practice to employ aqueous emulsions as coolant/lubricants in hot rolling and it would be advantageous to use water-based lubricants in cold rolling of aluminum. The objection to such a water-base coolant/lubricant system, particularly in cold-rolling, is the presence of this coolant/lubricant on the outgoing strip, since either the lubricant components, or the water base, or both, tend to stain aluminum. This tendency to stain is, of course, dependent on the amount of coolant/lubricant remaining on the strip after passage through the mill, the small amount carried through the roll bite in the particular region where the work roll is in contact with the strip being insufficient to cause subsequent staining problems. However, in the usual "flood lubrication" practice significant amounts of the coolant/lubricant come through the roll bite, around the edges of the strip; in consequence, some coolant/lubricant often splashes onto the surfaces of the outgoing strip. The occurrence of coolant/lubricant on the outgoing strip in local or general deposits of appreciable thickness is objectionable from its tendency to subsequently stain the aluminum.